The first season of Disney XD's animated series
"Marvel's Avengers Assemble" is coming to a close Sunday (May 25) with "The Final Showdown," which sees
the Tesseract now in the hands of the Cosmic Skull and the world is in catastrophic peril.

Check out these sneak peek clips. Above, Hulk and Hyperion duke it out, while below, get your first look at Thanos, who is making his debut in the first season finale. Thanos is a supervillain born on Saturn's moon Titan. Maria Hill is also expected to be introduced in the final Season 1 episode, though she is not featured in either sneak peek clip.

"Marvels' Avengers Assemble" Season 1 finale airs Sunday, May 25 at 9 a.m. ET/PT on Disney XD. A Season 2 has been ordered but there is no premiere date announced yet.